False twisting apparatus for tow



; J. w. SMITH FALSE TWIST'ING APPARATUS FOR TOW July 10, 1962 2 Sheets-Sheet 1 Filed Sept; 14, 1961 FIG. i

u a F I l JOHN w. SMITH FIG. 2 v INVENTOR.

ATTORNEYS July 10, 1962 J. w. SMITH FAL SE TWISTING APPARATUS FOR TOW 2 Sheets-Sheet 2 Filed Sept. 14, 1961 FIG. 3

FIG. 7*

JOHN W. SMITH INVENTOR;

ATTORNEYS United grates Patent @thee iht fi l Patented July 10, 1962 3,043,084. FALSE TWISTING APPARATUS FOR TOW John W. Smith, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Sept. 14, 1961, Ser. No. 138,031 8 Claims. (Cl. 5777.3)

The present invention relates to apparatus for producing false twist in continuous filament tow.

Due to the characteristics of the fibers of which they are composed, some tows have relatively little tendency to be coherent. Rather than remaining in a unitary, ropelike condition, such tows become stringy and unmanageable during handling when individual filaments separate from each other and flare out from the tow. One way of rendering such tows more manageable is to twist them, so that they become more rope-like and coherent. When for some reason it is not feasible to twist a tow, a false twist may be applied. A false twist provides a tow with some of the advantages of a real twist, but is easily removed subsequently since it is applied in alternating directions. To remove false twist it is only necessary to pull the tow out straight so that the turns in one direction cancel out the turns in the other direction, leaving an untwisted tow.

It is a principal object of the invention to provide an apparatus for applying false twist to tow.

The invention is illustrated in the accompanying drawings in which:

FIG. 1 is a side elevation of an apparatus in accordance with the invention, a tow being shown threaded therethrough;

FIG. 2. is a plan view of a portion of the apparatus of FIG. 1 but shown without the tow;

FIG. 3 is an enlarged perspective view of the tow guide assembly and drag bars of the apparatus of FIG. 1;

FIG. 4 is a schematic representation, in plan view, of the function of apparatus in accordance with the invention;

FIG. 5 is a representation similar to FIG. 4 with the tow guide assembly and drag bars in another position of operation;

FIG. 6 is a front elevation of the apparatus shown in FIG. 5; and

FIG. 7 is a representation similar to FIGS. 4 and 5 showing the tow guide assembly and drag bars in still another position of operation.

. With reference to FIGS. 1 and 2, elongated tow delivery rolls 2, 3 and 4 are driven in directions indicated by the arrows by a suitable power source (not shown). These rolls are spaced to grip and pull tow 1 from a source (not shown) to the left as one faces the drawing. The tow is fed onto the delivery rolls through a tow guide assembly which comprises two sets of guide bars 6, 7 and 8, 9, and a roller 10.

As shown more clearly in FIG. 3, the first pair of guide bars 6 and 7 and the second pair of guide bars 8 and 9 form confined pathways for the tow, holding the tow preferably in the form of a flattened ribbon lying in a plane parallel to that in which the guide bars 6 and 8' lie. The tow passes from the second set of guide bars 8 and 9 onto the guide roller 1%, from which it leaves the guide assembly. En route from the guide to the delivery rolls, the tow passes between the drag bars 11 and 12 which are disposed normal to the axis of the delivery rolls and which extend obliquely across the path of tow moving from the roller to the leading delivery roll 2.

As will be understood more clearly from FIGS. 1 and 2, the guide assembly and drag bars both are mounted on a support 5 which is fixed to a traversing carrier 15 for reciprocation along a path adjacent to the surface of the lead roll 2, parallel to the long axis thereof and substantially coextensive therewith. A motor 16 powers a transmission unit 17 which in turn drives a sprocket which engages a chain 19. A suitable means (not shown) is employed to reverse the output of the transmission or otherwise to provide for oscillation of the traversing carrier back and forth along its path lengthwise of the delivery rolls. The extent of each traversing run of the carrier is such that the point at which the tow makes contact with the lead roll 2 moves back and forth along the surface of the roll but does not run off of the end of the roll, i.e. the terminus of the traverse of the carrier in each case is such that the path of the drag bars stops short of the delivery roll end. I

As the tow passes over the roller 10, it collapses upon itself and, starting at a point between the two pairs of guide bars, its cross section is converted from one of ribbon-like configuration to one which is more nearly round or rope-like. While in such rope-like form, and en route from the guide assembly to the delivery rolls, the tow passes between the drag bars 11 and 12. As the traversing carrier moves back and forth lengthwise of the delivery rolls, the path of the tow extending between the drag bars 11 and 12 and the delivery rolls continuously changes. That is, there is continuous change in the point on the lead roll 2 at which tow first makes contact. Since the tow is running through the guide assembly and delivery rolls while being traversed back and forth, the position of the guide assembly and the position of the tow on the delivery rolls are spaced laterally from each other, the latter lagging behind in its traverse. Thus, as the guide assembly moves, the tow is pulled across and breaks over the surface of one of the drag bars. The action of the drag bar in cooperation with the movement of the tow along its own axis and the rotation of the delivery rolls is such that a twist is induced in the tow. During movement of the traversing mechanism in the opposite direction, the portion of tow traveling between the guide assembly and the lead roll is forced to break over the surface of the other drag bar and a twist in the opposite direction results. Therefore, as the traversing carrier is oscillated back and forth in its path of travel, generally parallel to the axis of the rolls, twist is induced in the tow first in one direction and then in the other. This alternating twist remains in the tow as it passes onto and through the delivery rolls 2, 3 and 4.

The twisting action is illustrated in FIGS. 4 and 5. In FIG. 4, the traversing carrier is moving to its right, toward thebottorn of the drawing as indicated by the arrow, so that the tow breaks over drag bar 12 and left-hand twist results. Travel of the carrier in the opposite direction as illustrated in FIG. 5 causes the tow to break over the surface of drag bar 11, resulting in right-hand twist in tow portion B as shown in FIG. 6.

inasmuch as the position of the tow on the roll 2 lags behind the position of the guide assembly, the guide will reach the limit of its travel in a given direction before the tow reaches the limit of its traverse on the roll 2. Then for an instant immediately after the guide has begun its trip in the opposite direction, a condition as represented in FIG. 7 will prevail. At this point in the operation, the drag bars are spaced directly opposite the point on the roll 2 at which tow is being received. With the carrier in this position, the tow does not break over either of the drag bars and no twist is applied to the V tow, this being the moment at which the direction of aoaaoes 3 bars 11 and 12. While twistis being induced in that portion of the tow (see B, FIG. 6) extending between the drag bars and the lead roll 2, twist of the opposite direction results in that portion of the tow (see A, FIG. 1) extending between the guide and the drag bars. Much, if not all, of the twist in the tow passing onto the lead roll stays in the tow and is carried along as the tow is discharged from the rolls 3 and 4. Thus as the tow is so discharged it contains an alternating twist. The twist in the portion of the tow between the drag bars and the guide assembly is largely a standing twist which does not travel with the tow to any substantial degree but is wound and unwound repeatedly in synchronization with the traversing movement of the guide assembly back and forth from one end of the delivery rolls to the other.

The guide bars 6, 7, 8 and 9 may be formed of stainless steel rods of A inch diameter, 846 inches long, the bars being spaced approximately /8 inch apart for tows commonly used. The drag bars may be of similar sizes and spacing, although a somewhat wider gap may be preferable due to the round configuration of the tow passing therethrough.

For best results, the tow 1 passing through the drag bars 11 and 12 should form an included angle of about 30 to.45. That is, the angle between the root end of a drag bar and that portion of the tow between the drag bar and the roller should be preferably in the range of 3045 The degree of twist depends upon the rate of traverse relative to rate of tow travel. Apparatus of the invention was successfully operated with a traverse stroke of 4 43.5 inches at a constant rate of one stroke every four seconds, when used on a 16 denier per filament, 32,000 total denier tow, having 4 crimps per inch and traveling at a speed of 284 meters per minute. This resulted in a change in false twist every 18.95 meters of tow. The point C in FIG. 1 illustrates the locus of a twist change in a tow.

The drag angle between the tow portion B (extending between the lead roll 2 and the drag bar 11, FIG. 6) and a plane normal to the axis of roll 2 (and passing through drag bar 11) is a function of the ratio of the linear tow speed to the linear speed of the traverse of the guide assembly. Thus the drag angle bears a direct relationship to the degree of twist induced. In the example referred to, this latter angle was calculated as 284 Tan ozor about 3.3

While the invention has been described in detail with particular reference to a preferred embodiment thereof, it will be understood that variations and modifications can be eifected within the spirit and scope of the invenition as described hereinabove and as defined in the appended claims.

7 I claim: 1'. Apparatus for applying false twist to tow comprising a driven deliveryroll means, a guide means for feeding tow to said roll means, a pair of drag bars embracing and extending obliquely across the path of tow between the guide means and the roll means, and means for oscillating the guide means and drag bars as a unit lengthwise of the roll means wherebyto traverse the point of tow feedback and forth along the roll means.

2. Means for applying false twist to a running tow comprising a pair of driven delivery rolls for pulling the tow, a tow guide for maintaining in a rounded, rope- 4 i like form tow fed to the rolls, a pair of substantially parallel tow drag bars spaced to provide a passage for rtow therebetween and positioned in the path of tow between the guide and the rolls, and means for oscillating the guide and drag bars as a unit along a path spaced from and substantially parallel to the feed rolls.

3. Apparatus for applying false twist to tow comprising driven delivery rolls, a guide assembly for feeding tow to said feed rolls, a pair of drag bars embracing the path of tow at a point between the guide assembly and the rolls, a common support for the guide assembly and drag bars, and means for oscillating the support lengthwise of the rolls so as to continually change the point of passage of the tow onto the rolls, said drag bars being so disposed that when the support is traversed in one direction tow fed to the rolls breaks over one guide bar and during traverse in the other direction tow breaks over the other guide bar.

4. Apparatus for applying false twist to tow comprising a pair of delivery rolls, a guide assembly for feeding tow to the rolls, a traversing support for the guide assembly adapted to traverse in a path generally parallel to, offset from and coextensive with the rolls, and a pair of drag bars carried by the traversing support positioned normal to the axes of the delivery rolls, and disposed in such a way that tow passing to the rolls from the guide assembly breaks over one bar when traverse of the support is in one direction and over the other bar when traverse of the assembly is in the opposite direction.

5. False twisting apparatus for tow comprising roll means for continuously receiving and discharging tow, means for feeding tow to said roll means, and means for oscillating said feeding means along a path which is spaced from and substantially parallel to the roll means, said feeding means providing drag means through which tow passes at an acute angle said drag means comprising a first surface over which tow breaks en route to the roll means during traverse of the feed means in one direction and a second surface over which such tow breaks during traverseof the feed meansin the opposite direction.

6. False twisting apparatus for tow comprising driven delivery rolls, a tow guide, a pair of spaced, parallel drag bars embracing and extending obliquely across the path of tow en route from the guide to the rolls, normal to the roll axes, and means for oscillatiang the guide and drag bars as a unit along a path parallel to and spaced from the rolls.

7. Apparatus as definined in claim 6 wherein the drag bars are disposed at an included angle of 30-45 to the path of tow from the guide and the oscillation path is substantially coextensive with the axes of the rolls.

8. Apparatus for applying false twist to tow comprising driven delivery rolls, a guide for feeding tow to the delivery rolls in a generally round cross-sectional condition, a pair of drag bars embracing and extending across the tow path between the guide and the rolls at an angle of about 30-45 to said path, and means for traversing said guide and said drag bars together as a unit back and forth in a path parallel to and substantially coextensive with the delivery rolls.

Lipps, Feb. 13, 1917 Hansen June 24, 1952 

